1. Field
This disclosure relates generally to sensor devices, and more specifically, to using rotational data acquired from an accelerometer and a magnetometer in a system to calibrate a gyroscope sensor in the system.
2. Related Art
Recent trends in consumer electronic devices include addition of a variety of motion and positional sensors in such devices. These sensors include accelerometers to measure device acceleration or position with regard to gravity or other acceleration forces, magnetometers to measure device orientation to a magnetic field, and gyroscopes to determine angular velocity of the device for a variety of applications. Inclusion and intelligent use of multiple types of sensors has been called “sensor fusion.” Useful application of sensor fusion involves accurate readings from all the sensors, and importantly from the gyroscope.
Gyroscope sensors used in the devices discussed above are typically microelectromechanical systems (MEMS) devices. MEMS gyroscopes can be susceptible to bias errors, in which, for example, the output of a stationary (not rotating) gyroscope is not zero. MEMS gyroscopes can also be susceptible to gain errors, in which the gyroscope fails to measure accurately the angular rotation of the system incorporating the gyroscope. Such errors can result in significant errors when using the gyroscope for applications involving navigation or requiring rotational accuracy.
Typically, MEMS gyroscopes are calibrated for bias and gain errors by the manufacturer prior to shipping the devices to customers. But once the gyroscope is in the field, there may be a need to recalibrate the gyroscope to maintain accuracy. It is therefore desirable to provide a mechanism by which MEMS gyroscopes can be recalibrated in the field.
The use of the same reference symbols in different drawings indicates identical items unless otherwise noted. The figures are not necessarily drawn to scale.